The present invention relates to fluidic oscillators for use in vehicle washer systems and more particularly to a fluidic oscillator for vehicle windshield washer systems in which a housing, which can be commonly used on different vehicles, incorporates a fluidic oscillator element, hereinafter termed a xe2x80x9cfluidic insertxe2x80x9d, which carries a physical silhouette or pattern of a fluidic oscillator and is adapted to create different deflection angles. As used herein, the term xe2x80x9cdeflection anglexe2x80x9d means the angle that the jet of wash liquid makes as it exits the outlet in a plane orthogonal to the plane of the silhouette, and the term xe2x80x9cfan anglexe2x80x9d is the angle made by the jet sweeping back and forth between the boundaries of the outlet in the plane of the silhouette.
Stouffer U.S. Pat. No. 4,508,267 entitled LIQUID OSCILLATOR DEVICE and Bray, Jr. U.S. Pat. No. 4,463,904 entitled COLD WEATHER FLUIDIC FAN SPRAY DEVICES AND METHOD disclose fluidic oscillators which have proved to be highly successful. They typically comprise a housing in which a fluidic insert element having a silhouette of a fluidic oscillator is inserted into the housing. The silhouette of the fluidic oscillator typically is of the type disclosed in FIGS. 2A and 2B, FIG. 2A being from the aforementioned Stouffer U.S. Pat. No. 4,508,267 and FIG. 2B being Bray, Jr. U.S. Pat. No. 4,463,904, it being appreciated that other forms of fluidic oscillators may be used. This type of fluidic oscillator has a power nozzle PN issuing a jet of windshield washer liquid JW into an oscillation chamber OC towards an outlet OL which issues the jet of wash liquid into ambient where it is oscillated in a fashion so as to cause it to rhythmically be swept back and forth so as to cause the liquid jet to break up in droplets of predetermined size configuration or range so as to impinge on the windshield at a predetermined position under various driving conditions as disclosed in U.S. Pat. No. 4,157,161. In the Bray, Jr. patent, the Coanda effect wall attachment or lock-on cause a dwell at the ends of the sweep which tends to make the spray heavier at the ends of the sweep than in the middle. In the Stouffer U.S. Pat. No. 4,508,267, the configuration of the silhouette is such as to cause the liquid oscillator issue a swept set fan spray in which the liquid droplets were relatively uniform throughout the fan spray and the uniform droplets provide a better cleaning action.
In the manufacture of windshield washer nozzles, it has been found desirable to provide one housing on different vehicles which thereby reduces the cost of housing design and the tools. However, this requires creating different deflection angles in the fluidic inserts which contains fluidic oscillating element per se.
It has been found desirable to provide variable deflection angles. In one approach disclosed in FIGS. 2A and 2B, a fluidic oscillator of the type disclosed in the aforementioned Stouffer U.S. Pat. No. 4,508,267 incorporated a step or bump B at the outlet OL of the fluidic circuit to create up to about a 6xc2x0 deflection angle oscillator. The step appears to deteriorate fluidic functions and create adverse side effects such as:
1. Inconsistent and unreliable deflection angles due to the high sensitivity of the flow to the step height,
2. Reduced fan angles and flow rates because the step or bump could reduce the throat area,
3. Smaller than normal droplets caused by the fluid impact on the step or bump,
4. Messy spray caused by fluid impact on the step or bump,
5. Degraded waves as a direct result of the destruction of fluid functions made by the step.
Moreover, the deflection angles of the fluidic washer nozzles can be adjusted by using the taper at the floor of the fluidic insert as disclosed in the aforementioned Bray, Jr. U.S. Pat. No. 4,463,904. This eliminates the impact between the fluid and the step. Therefore, the spray is usually not as messy, and the wave is usually not degraded until the taper reaches about 10xc2x0 to 12xc2x0 when the flow begins to separate from the floor of the insert. The deflection angles are not as sensitive to the taper as it is to the step. However, with the use of a large taper, the spray becomes much thicker, and it makes the reading of the deflection angle very difficult and inconsistent because it is hard to find the center of a thick spray.
According to the present invention, the problem discussed above is solved by the use of a reverse taper at the outlet of the fluidic insert to adjust the deflection angles of the fluidic wash nozzle. This reverse type allows one housing to be used for several different types of vehicles which have different requirements for deflection angles. It allows the creating of different deflection angles in the fluidic insert per se rather than designing a housing and tools for the different deflection angles desired. Thus, according to the present invention, the windshield washer element has a housing with a rectangular chamber having formed therein a silhouette or physical pattern of a fluidic oscillator which may be of the type disclosed in the above-referenced patents. The fluidic oscillator silhouette has an oscillation chamber having an upstream end coupled to the power nozzle for issuing a jet of wash liquid into the oscillation chamber and a downstream end having an outlet aperture perforation for issuing wash liquid to ambient. The oscillation chamber includes means for causing the jet of wash fluid to rhythmically sweep back and forth between the side walls and the oscillation chamber and issue in a sweeping rhythmic fashion and through the outlet. According to the invention, the top and bottom walls of the oscillation chamber diverge for a predetermined distance in a downstream direction and then converge towards each other through the outlet aperture. For different housings, and different physical applications, the degree of the taper can be changed to accommodate the deflection angles required by different vehicles, to thereby reduce the cost of housing design and the tools.
The invention retains the droplet size without causing a detrimental increase in smaller droplets which are more adversely affected by wind and air flow effects over the vehicle. One of the basic objectives of the fluidic windshield washer nozzle is to have a fan spray which has a designed or predetermined droplet distribution through the fan and the present invention retains desired droplet distribution while providing the uniform droplet distribution of Stouffer U.S. Pat. No. 4,508,267.